If sintheta + sin squaredtheta = 1
then, cos squaredtheta + cos to the power of 4theta = ?

Asked by bjayanta | 8th Jul, 2015, 07:09: PM

Expert Answer:

G i v e n space t h a t space sin theta plus sin squared theta equals 1... left parenthesis 1 right parenthesis W e space k n o w space t h a t space s i n squared theta equals 1 minus cos squared theta T h u s comma space e q u a t i o n space left parenthesis 1 right parenthesis space b e c o m e s comma s i n theta plus 1 minus c o s squared theta equals 1 rightwards double arrow s i n theta minus c o s squared theta equals 0 rightwards double arrow c o s squared theta equals s i n theta... left parenthesis 2 right parenthesis S q u a r i n g space b o t h space t h e space s i d e s space o f space t h e space e q u a t i o n comma space w e space h a v e comma c o s to the power of 4 theta equals s i n squared theta... left parenthesis 3 right parenthesis A d d i n g space e q u a t i o n s space left parenthesis 2 right parenthesis space a n d space left parenthesis 3 right parenthesis comma space w e space h a v e comma c o s squared theta plus c o s to the power of 4 theta equals s i n theta plus s i n squared theta space space space space space space space space space space space space space space space space space space space space equals 1 space space space space space space space space space space space space space space space space space space space space open square brackets f r o m space e q u a t i o n space left parenthesis 1 right parenthesis close square brackets T h u s comma space t h e space v a l u e space o f space c o s squared theta plus c o s to the power of 4 theta space i s space 1.

Answered by Vimala Ramamurthy | 9th Jul, 2015, 08:39: AM